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Spiking egt's

R

ryanblacksvt

I'm the Dork who ran 14.9 on PassTime. :)
Joined
Jul 28, 2003
Messages
9,083
Location
Loganville,GA
Ok what are yalls thoughts on why my egt's are spiking. They are still doing it, at w.o.t in boost they can spike as high as 1600(could go higher but I let off the gas). A friend and I got to talking and he brought up a very valid point, my temp guage on the instrument panel stays normal the entire time even when the egt's spike, and even when cruising and they are constantly at 1400-1450 the temp stays normal in the panel.

Could this be a burnt egt probe thats causing this reading of the higher egt's??? I just dont even drive the car anymore cause I am nervous to start melting things till I get this issue taken care of IF the egt's are even being read correctly.
 
do you know if it is one bank or both banks? I know that at this time I have one bank running leaner then the other and that causes more heat ...
 
I have no idea, I know the rear bank is running rich per the codes I threw p0172 & p0175 ,but this is the reading at the egt guage.
 
sorry, i have no pyrometer. i have both banks running rich. could be the tune, but likely the BOV is a contributing factor.
 
Your EGT's are getting higher when you go WOT? Wow... amazing... can't imagine why that would possibly happen :p

By temp gauge on the instrument panel... you mean the coolant temp gauge. You would likely not see any change on that gauge over a fairly large range of coolant temp. However, your EGT won't really cause that to change unless they are considerable over a long time period.
 
^Ok I didnt know if the temp guage would be going higher or not when the egt's went way up.

And yes at W.O.T they are spiking Barge but 1600 degrees is NOT SAFE, thats what I am trying to find out, why are they going soo high:shrug:
 
ryanblacksvt said:
^Ok I didnt know if the temp guage would be going higher or not when the egt's went way up.

And yes at W.O.T they are spiking Barge but 1600 degrees is NOT SAFE, thats what I am trying to find out, why are they going soo high:shrug:
Click to expand...

You need to do some datalogging to see if you have both banks running the same first then you need to log the wideband on the datalogs too so you can see where the motor is running lean because too much timing pulled causes the exhaust gases to be hottor too. I thought you were buy a tune?
 
Too lean or pig rich will cause the EGT to rise that high. The lean A/F reason is obvious but also unburnt fuel can be lighting off in the primaries as well. Some people think dumping a ton of fuel will help cool a boosted engine but there is definitely a point when too much is too much.

A well tuned boosted engine should be in the 1400 range. Above 1500 is the risky zone. IIRC Tom had a great post about EGT's on the Duratec back on the old forums.
 
DemonSVT said:
Too lean or pig rich will cause the EGT to rise that high. The lean A/F reason is obvious but also unburnt fuel can be lighting off in the primaries as well. Some people think dumping a ton of fuel will help cool a boosted engine but there is definitely a point when too much is too much.

A well tuned boosted engine should be in the 1400 range. Above 1500 is the risky zone. IIRC Tom had a great post about EGT's on the Duratec back on the old forums.
Click to expand...


Dumping extra fuel will definately cool the EGTs right up to the point where the raw fuel begins burning in the port or manifold.

The acceptable temp range is largely determined by the exhaust valve material / and design. At 1600 deg. F, your exhaust valves will not last long at all, unless you replace them with Inconel or hollow, sodium cooled valves. For the Production Duratec valves, I definately wouldn't exceed 1500 deg. F. One other thing to keep in mind is that temps vary in the exhaust manifold and ports depending on where you are measuring. As an example, if you are measuring right outside the head, say maybe no more than 3/4" away from the flange, you have a pretty good approximation of the port temp and consequently the exhaust valve temp. However, if you measure a little further down the manifold, near the collector (on a stock type manifold) the temp may actually be 50-75 deg. F higher than the port temp from interaction affects of multiple cylinders.

So, since I've only provided supporting technical info here, I'll get back on the specific subject, do what Joey says, and get the lean spots out of the tune. lol.
 
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